. The steam-engine and other heat-motors. aft, and we find that 155 pounds concen-trated at the crank-pin would have the same moment. In addi-tion there is 55% the weight of the connecting-rod to be con-centrated at the same point or a total of 155 and 75 = 230 pounds. TIT2The above weight would have a centrifugal force of —5-. gti 402 THE STEAM-ENGINE AND OTHER HEAT-MOTORS. At 210 revolutions per minute this would be230/4X22X22X5X210X210 82 \ 7X7X6X60X60 2900 lbs. WV2 The horizontal shaking force would be —^- cos 6 = 2900 cos d and the vertical shaking force would be WV2 gR sin 0 = 2900 sin A
. The steam-engine and other heat-motors. aft, and we find that 155 pounds concen-trated at the crank-pin would have the same moment. In addi-tion there is 55% the weight of the connecting-rod to be con-centrated at the same point or a total of 155 and 75 = 230 pounds. TIT2The above weight would have a centrifugal force of —5-. gti 402 THE STEAM-ENGINE AND OTHER HEAT-MOTORS. At 210 revolutions per minute this would be230/4X22X22X5X210X210 82 \ 7X7X6X60X60 2900 lbs. WV2 The horizontal shaking force would be —^- cos 6 = 2900 cos d and the vertical shaking force would be WV2 gR sin 0 = 2900 sin A good counterbalance can be obtained by the addition of weightsformed by prolonging the crank-arm in single- or overhung-crankengines and prolonging both arms in double-crank arm product of the added weight and the distance of its centerof gravity from the center of the shaft must be 1550 in the abovecase, or in general the product of the weight and its gravity armequals the sum of the moments of all the rotating Fig. 220. In general, rotating weights cannot be balanced by a singlerotating weight, as it is not practically possible to put the centerof gravity of the counterweight in the plane of revolution of thecenter of gravity of the unbalanced weights. For equilibriumit is essential that the moments of all the forces exerted by theweights about any axis should be zero. In statics, the forceexerted by a weight is equal to the weight; in dynamics, the forcemay be put proportional to the product of the weight and its lever-arm if the comparison is restricted to bodies having the samenumber of revolutions; if the number of revolutions of the bodiescompared differed, then their forces would be proportional to theproduct of their weight, their lever-arm, and the square of thenumber of their revolutions, as is apparent from the formula for WV2centrifugal force, —^-. SPEED VARIATION CONTROL. 403 In Fig. 220, suppose that we wish to counterbalance equivale
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